Heater



W. D. HALL.

HEATER Patented oct. 25, 1949 U NITED S TATES PATENT OF Fl CE HEATER -William DJHaLll, Elkins, WJVa.

Applicationflctober 1, 1943, Serial No.l 504,622

12 Claims. (01." 23'7133) L'Imstinvention relates'to':heaters='aas well aspto tin section-.01" a gearwbox. Figurer3sillustratesea control systems'therefor, and'has for its objects 1 gear train. Figure-41is a'sectional'viewoftherbox the provision of an'automobileheaterthat:opcontaining the wick, 1 this :-sectionbeing taken erates independently 'of the automobile engine, aalonglineA-J of Figure-3. Figure-5-is one:circuit the provision'of a small unitthat will'give a large diagram of the zelectrical -parts. -Figureo6 illusamount of heat; the provisionof a heater which .tratesza detail relating to closing. theairsupplyzin is safe inoperation, the provision of an" automoevent ofroverheating. "bile heater that can-.:be started automatically In. Figure 1 is shown the-.fire' wall of arrrautosuch as :byza'time :clock 'beforethevautomobile .mobile, separatingethe-enginecompartment 12 is: started, the provisionof a heater havingianad- 1:10 from the passenger compartment I I. :The engine ju ta'b a ou of a p p o 'of compartment has the usual iinternalucombustion meansin a wick burner'foricontrolling the height engine not shown, for driving. the; :car;:- and; the of thewick;'an'd the. provisionof numerousother passenger compartment may be closedin-gany features, which inhere in .the'structure'tand-will -.well --.known manner a such: as :by windows; and be obvious to experts from'za studyzof thefollowing r 15; d -M()unted n,,fire 11 II] i sup orting description. these 13 which -:mechanically supports electric iIn carryingout the foregoing Objecflisv provide amotor- M. :The motor l4 drives. circulatingtafan [5 in addition to the gasoline tank of thecar OIYQQUtO- and; alggtheegghaugt pump ['6 The -motorj I4 is mobile, a supplemental 'small' gasoline ta :sseparated from the exhaustwpumprby antinsulata p y PArmngemenfl mad-e101 =ring plate-l 4min order. topreventfundue temperafilling this supplemental tank from the mainone sture rise of .thewmotor. A-fuel line l'l supplies r y a a Gasoline s a n omelet-toitheygasoline tank 21. Line l'lsatiitstop the pplemental tank by'mea so arid .endmay:'connect to the. fuel lineofthe automobile burned under therinflu'ence 'of' strong suction. ,.adjacent thev=carburetor, or it may'operate :by

Stro g Su t on drawing "away from fifiqgravityfeed from the 'carburetonort'it may conorea es a very hot 'fiameWhich'not"only'SfJ f tnect'to a-easolinetankzwhich 'is independentof like a blow torch but has f-heat ":output \slm'llar athezautomobile gasoline"supply. If 'the' line ll t eretoe 81 p p leadsflom'the' sis-tapped into the'fu'el lineof the automobileaclbus io a be iw is in theenginecompart- "jacentithe carburetor, it. is obvious that the fuel ment of theautomob e; through-W118 fi EflOrpump of tthe: automobilewill"pump tank 2| to the'car' andcirculates' insideof theradiator 'comvitsrcut-o'fi 'point'wh'enever the car engine is runpartment of the 'automobileeheater. -The" suction fining; :When the car engine stops, enough fuel will P p e eads back through the wfire' wall finto remainzin'tankil' for several hours of operation the engine compartment and conneetionsis made t-and-since it i :probablgthe ca will be operated from it to the suctionblower. rAsla result of this 9,3 a;ga;i-n Tbefore the heater "has operated several construction, the combustiortgases-arei conducted. hours, 11 v t txt -h t w usually throu h he pas r: par ment undernconshe-su lied with sufficientgasoline. Float system ditions of par-tialvacuum and therefore-in event 1'!!! shown fdiagrammatically, arranged to close of a leak in he s ion pip oh tses an "the fuel"line'whenthe"tank-"2I is filled to a-suites ape into the. pa eng r ompartment. .In event table :point, such: as two-thirds fiill. "The" float of a large leak that will'de's-troy the vacuum 0011- =rsystem 20 is shown cooperating with avalve l 9, ditions, the fire in the combus'tionchamber willbe however these are not shown in detail 'for'the snufied out due o" lack of l, Since t s e reason thatnumerous priorart arrangements are vacuum which draws air into the combustion available to teachone skilled in the art how "to chamber through'smallholes leading thereinto. 4-45 "out :ofiff 'ther *flow of gasoline when a prede- The wick'may' be adjusted to a'pre'determined 'termine'd level in'atank' is'reached. A=wick 22 h i h ma ally y imp y r a ha dle 'zexteridsfiown and into tank 2 las well as extends in h p e r ompar en 'This an the up through' chamber 23 and outthe to thereof other features of 'my'inventioncan'bestbe unays-elaborated upon later. A 'hood 24'is located derstood'by reference to the detailed descrip-emo over the burning wick and gathersthe' hot" gases tion which 'i follows the explanation of 'the ftherefromzaand leadsthem to radiator 'pipe 25.

drawings. T-From the radiator pipe- 25," the hot gases pass to In the draw'ings,--Figure;1risra-sectional'viewof eexhau'stvpipeiifi, to exhaust'blower IE, and 'out theHheater. Figure 2 iszan elevation View-of-the exhaust :pipe '21, 'jThe suction-exhaust bloweri'is containinathe a sa howing, 5-5 e'mountedionltherrearsend or motor-14' and sidriven by the shaft of that motor, the same shaft that drives fan I 5.

Mounted on the elongated radiator pipe are numerous fins 3|, and the portion of the heater including these fins which is in the passenger compartment is enclosed by an ornamental and mechanically useful casing 28. Casing 28 has suitable deflectors 29 mounted on the front panel 39 thereof in any well known manner.

The burning fuel is located in a combustion chamber 00. On top of the combustion chamber I is a casing 34 containing bimetallic strip 33, the function of which will appear later. Located within combustion chamber M0 is the wick chamber 23, and the wick 22. The wick is aperated up and down by certain toothed wheels 40, shown in Figures 1, 2 and 4. Toothed wheels 40 are mounted on shaft 39, this shaft being operated by knob 32. Likewise mounted on shaft 39 is gear wheel 45 which engages gear 46, the latter driving a shaft carrying toothed wheel 40a. If the operator turns knob 32 counterclockwise (as viewed by him sitting in the car) the wheel 40 of Figure 4, being mounted on the same shaft will turn in the same direction as knob 32, however due to the choice of the draftsman the wheel 46 as viewed in Figure 4 would be turned clockwise. As Viewed in Figure 4, when shaft 39 rotates clockwise, toothed wheel 40a is rotated counterclockwise and the Wick is moved upward. When the toothed wheel 40 as viewed in Figure 4 is rotated counterclockwise, the wick moves down wardly.

In order that the operator in the car may always turn the wick to any desired height, I have provided a special mechanical arrangement best shown in Figures 2, 3 and 4. A pinion 50 (located in box 206) is mounted on shaft 39 and engages idle-wheel 5| which is mounted on shaft 52. The idle-wheel meshes with gear 54 which is supported by shaft 53. The shaft 53 carries a pawl 56 operating in connection with a ratchet wheel 55. When the shaft 39 is rotated clockwise (as viewed in Figure 4) so as to cause upward motion of the wick 22, the gear 54 moves in the same direction and pawl 56 operatively engages ratchet wheel 55 and rotates the latter along with shaft 38, gear 42, and toothed wheels 4| all in the same direction as shaft 39. Gear 43 meshes with gear 42 and drives toothed wheels Mu. in a direction opposite that of 4|, hence toothed wheels 4| and Ma. cooperate in moving the wick upward when shaft 39 is rotated clockwise as viewed in Figure 4 (counterclockwise as viewed by the driver sitting in the drivers seat).

When the driver rotates shaft 39 in a direction opposite that mentioned in the foregoing paragraph, namely when he rotates shaft 39 clockwise as he views it (counterclockwise as viewed in Figure 4) the shaft 53 is rotated in the same direction as 39, and the pawl 56 slips with respect to ratchet wheel 55 in absence of other forces. Hence the toothed wheels 4| and Ma play no part in driving the wick downwardly, although as was mentioned earlier they do assist in driving it up. Toothed wheels 4| and Ma are quite free in their action and are rotated by the moving wick as it moves down, but these wheels play no part in any functional sense in moving the wick down.

It is apparent that whenever the wick is moved down by rotation of knob 32 to approach its off position that toothed wheels 4|] and 40a will drive the wick down until it passes so low that it barely disengages wheel 40 and 40a. Further rotation of knob 32 is of no effect, it merely rotating toothed wheels 46 and 40a which are not in engagement with wick 22. Hence it is obvious that the wick 22 is always at the same starting position when the heater is ready to be started after having been turned off, namely it is always just below wheels 40 and 40a. When the heater is again turned on, the toothed wheels 4| and Ma are again in action and drive the wick up a fraction of an inch until it is again engaged by toothed wheels 40 and 46a, and the wick is then driven upward in proportion to the rotation of knob 32. Hence, knob 32 may be accurately calibrated for various wick heights. Various wick heights create various amounts of heat output and hence the heat output may be somewhat varied.

The electrical system will now be explained. The line L from the car battery lead to switch SW which may be a time clock, thermostat, or other switch, (switch SW may be omitted if control is effected only by knob 32). Switch SW is only used for automatic control and is shorted over when manual control by knob 32 is employed. When switch SW is a time clock, it may be adjusted to turn on at 7:45 A. M. for example in event a driver normally starts his car at say 8:00 A. M. The night before when the driver set the clock, he likewise turned the knob 32 clear on but of course this had no effect since switch SW is open and will not supply any operating current until 7:45 A. M. At 7:45 A. M., the switch SW will supply current to igniter 51 through bimetalilc strip 33, contact strip 58 and shaft 39. The motor M will likewise be energized. The igniter will ignite the wick at 7 A. M. and a flame will continue. If for some reason the driver does not show up, the heater will not burn indefinitely for it will run out of gasoline after operating a few hours and stop. After the heater has run out of gasoline, the flame will cease and bimetallic strip 33 will cool reclosing the circuit to igniter 57. The heavy current drain -of igniter 51 will operate the cut-out switch, thereby stopping the system. The cut-out will be tripped back in by the next operation of shaft 39 if suitable means are thereby employed.

It is apparent that plate 58 will make suitable contact with arm 59 for any wick height, as determined by shaft 39. If it is desired to vary the motor speed depending on wick height, this may be done by making 58' a resistance and so selecting the resistance value that the speed of the motor is proportional to the heat output of this wick 22. This will always effect uniform temperature of the air blown from 30.

As safety precautions, the fuel pipe I! is provided with a cock I8 which opens only when knob 32 is turned on; and the air inlet holes 25' are covered by a plate 63 which is released by a bimetallic strip 60 in event of an excess temperature in the combustion chamber. The wall 6| of chamber I supports bimetallic strip 60 which normally holds plate 63 above holes 25'. In event of excess temperature the-plate 63 is released and covers holes 25 thus snufiing out the flame for lack of air supply.

The holes 25 are located between the fire wall and the chamber 400 so as to minimize the effect of the automobile engine fan and the strong wind set up dueto motion of the car. Holes 25'. are of such size, and the pipe 25 is of such size that the fuel will not satisfactorily burn unless motor I4 is running. For example, if motor I4 is not running, there is no place for unburnt aging v of many apart oof szthe sexhaust path cannot 3 xcreateea dangerous .aoondition'; forrthezifia-me will ::die outxpromptly-.;upontthe stoppagezofrsuitable lair. JW hen'tthe heater :.--is turnedcofi, lithe ewick ;.is of :corirse retractedrandaalsotthesmotorr; stops.

26 neric reclaims ;;set :torth ebelow :sshonld :not she climi-ted {to :the precise :iorm ridisolosed; 25641168 I-I -deSi16-XGOflpl QtectnnotiiOnlyi1IhQLEPEeCi-SSHEQImimS- closedby .me butaallr-equivalent forms.

.Lclaim-tol'have inyented: 1. .aiutomobile {heating system (1 comprising a smalli incl-.tank-sepa-rata from! the; fuel tankcof the automobile; v. a combustion. chamber; A La wick ,wetted. in said first-named; tank. .anclsextending Stopping of the motor apparently has aneeffiec al o .iintotsaid.combustionchamber; an .igniterior rtendingi tosreact :baekwinto; thezcombustion: chamlbert-iordl haveioundc'thatteven ifcthe apparatus is cmodi-fied solthe :mickris:noteretracted that ,the istoppageeot thenmotor: willi'rliterallycblowziout igniting. the: end .of-, the wicksthat. is inthe: comvibustion 1 chamber means ,supporting asaidhfirst- .named fue1...tank,,said combustionchamberssaid ,wick,,.and, said igniter to position them a11; 01'1ttthefiame. jecannot-a'explain;tholexactrreasonttor U 5 side the passenger compartment,.ofwtheuautomothiszeffect.

Asziauariationsintthe preferred; dorm; oflzsatety Lprotection;sh0wntn.;=figure:6,LIi mayv-zalsogprotect aa'gainst :overheatmg rzby euse uOf tan overheating thermostatcQTa located in thezelectricali liner-and suitablyeplaced orznearzanygpart'. 0t. thee-heating systems-thaws, liableztoebe overheated.

-.Some increase: .in'; the vprobabilityeof 111511113101! SIS .zattained if= a-resistance: Rizand-za. thermal switchl -areiused with'anearrangement ysuchzthatzresistor eRiheatst-thermalzswitchzl to; start the motor cirscu'it avithinia few: secondsza-tter. igniterifal-reaches i nition-z temperature. wWhen the startin nof the motor isdelayed: ;igniters 1. 51 readily ignite the wick 1.22 if they mare within none-half .1-inch thereof, :"blltiii the :delayed. starting feature l is snot used thedsniters should 1369102211386. veryclose to the wick-sand iarrangedzito get-very; hot. {Their :cross=section"-mayaand" preferably, is vlarge so-qas to avoid cooling by the; air: blast; and:.-they.-:may

. further ,if desired -..be Educated Linea small -;cover which wilt, shield 1 themzfrom the) blast. :isuch ia "cover.'202= is shown over igInteraS'hini-Eiwre 4.

;.It is: apparentthat with rnyvconstruction, there "isz no; possible wayethatwunburnt gases; can enter the 1. passenger 1 compartment. Gasoline cannot a andidoes not burn intthe passenger compartment. -'Moreoverr.the combustionmhamber ;is separated from the (passenger; compartment-my. ther firerwall ,-of the :car, rso that cinuevent thBtidIiVBlwShOU-ld bet-involved; insanvaccident which might set la-fire :the gasoline in:theggasolinel-tankizfl, thenceupants will the protected. i'I he 3 gas tank :21 as i has been K stated, i is small and therefore I if; :it' :is broken 1 due: to ;crash-.up f 1 thevcar, no serious danger 1 will --result. By: smallbi Irmean l thefrta-nk .is of. suchvsize-thatw-it zwillifioperate :the; heaterg-at the inormal ra-te tor :noxrnoretharr fiyerhours. a'It :is vfurther z-apparent tha-tccombusticni con-editions in v-gasoline I tankz z I and chamber wfizare every pOSSibflityfiOf uncontrolled;combustionpm fires is quite remote pthe ionly: idangenbeinginevent; the

automobile should lee-involved 1 in .anzaccident that would radically idislocate .theparts orgefiectiai leak in thetank.

-It is noted that wexhaust pipe[24 :=Z5::Dasses "directly: from. the ecombustionechamber through the fire wall 4!) gii-nto .passengcrzcompartmentz I I Tests show that a surprising;amountnofiheat;:is: 'iconductedsbyi-theawalls' of:this;pipe,i-andi1that by :noimea-ns alhcf: the heat travels .int theradiator portionsoftthe heaterh-dueztosuc-ticn. i'lhe aheat transmission by conduction :iseffective; asnwellzas sefficient-iandsisevenco ras dcbynmakmg:thaiwalls ofypipe? 25 ,l-at leastto1and-includingionegvtraversal loft-the radiator portioneof tthe, heatenzrrelativcly I thick.

awhile eIzi'have illustrated .-one specific aembqdi- .ment-zchmy :mventionc Irwish: toa'statezthatnthe lbile means; adapted, to be connected, to ,the Liuiel ,suppl of the automobile, vfor iaddinsd asolinelto said .small fuel tankwvhenthe ,automobileensine is ,running and. stopping supply of gasolinej,.to

. said small tank when the automobile enginejis not running; meansfor. transmitting the heat generated in said. ,combustion chamber to the passenger compartment and dissipating the-same *therein, forced draft ,means for supplyingpair'tto support combustion to said combustion'chamber, and means operable to control said ig-niter'and draft means either when the automobile'engine'ds running or stopped whereby the heating system 'may be operatedwhen the automobile enginehas $0 stopped.

-2. .An automobile' heating system comprising-la relatively small fuel tank which will-be exhausted it operated without being refilled within five hours,- acombustion chamber [located nearby sald tank, a wick wetted at one end in saidtank and -eXtending into-the combustion chamber-at its other end, an electrical igniter-in'thecombustionchamber for igniting said wick; means: supporting all 0f the above recited parts-on -thetfire wall of an automobile in the engine compartmentQheat transfer means'for transferring the heat generated in said chamber to'zthe passenger compartment, means adapted to'be connected-to the'fuel supply of the automobile for adding-agasoline to said small'fu'el tank when 'the automobile -=enginedsrunning and stopping supply-of gasoline to 'said small tank when the automobile engine is 'not running; means for" dissipating the heat thus transmitted throughout the passenger 00m- -partment, electrically driven means-foreffecting to energize said igniter and "said electrical-1y 51 poor when-the motor, it is stoppedsandehencethe ,wf-uel tank of relatively small capacity which" will -'--be exhausted due to operation of the heaterafter no more than fivehours at the maximum-burn- 1 'ing rate, -meanssupporting said" tank to positio-n the same in the -engine compartment of amauto- ,cs mobileand separated irom the operative parts "of ''the automobile engine, .means driven bythe automobile engine for adding gasoline to "said tank. :when .the l automobile engine is-running and P ior stopping supply of gasoline to said tank-when N the automobile engine is not running, heatgenerating: means including a combustion chamber 1 mountedwinsaid engine compartment and being suppliedwith gasoline from said tankh-forhburnningusaidzgasoline irrespective whetherathetauto- 5 .mobile engine is running ornot, meanstontransferring heat from said combustion chamber to the passenger compartment of said automobile anddissipating the heat in said passenger compartment, and control means in the passenger compartment to control said heat generating means to start and stop the same independently of the operation of the automobile engine.

4. An automobile having a main gasoline tank, fuel pump, carburetor, and internal combustion engine for driving the automobile; and a heater for heating the passenger compartment of the automobile comprising a small gasoline tank separate from the above-named parts, a fuel line leading to said small tank and tapped between said carburetor and fuel pump, a combustion chamber, means for supplying gasoline from said small tank to said combustion chamber, all of the above-named parts being located outside of the passenger compartment of the automobile and separated therefrom by a Wall of the passenger compartment, a pipe leading from the combustion chamber through the wall of the passenger compartment and passing back and forth therein so as to act as a radiator and then passing back through the wall of said passenger compartment to the outside thereof, an exhaust pump located outside said passenger compartment for exerting suction on the end of said pipe that passed back through the wall of the passenger compartment, a circulating fan within the passenger compartment for circulating air in said compartment over said radiator, and a common motor for driving said exhaust pump and said fan.

5. An automobile heater comprising a gasoline tank and combustion chamber mounted adjacent each other in the engine compartment of the automobile, a wick wetted at one end in said tank and adapted to burn at its other end in said combustion chamber, an exhaust pipe for said combustion chamber which passes through the fire wall of the automobile into the passenger compartment where it passes back and forth to sufficient extent to act as a radiator, said exhaust pipe extending back out of said passenger compartment into the engine compartment, a suc-, tion blower in the engine compartment for creating suction on the end of said exhaust pipe that extended back out of the passenger compartment, a circulating fan for blowing air over said radiator, a common motor for driving said suction blower and said fan, and a control knob for controlling energization of said motor; said combustion chamber defining air inlet holes therein for admitting air to support combustion, the said holes being of such limited size as to prevent combustion from taking place in said chamber in event said suction blower stops.

6. I'he device defined byclaim 3 in which said heat generating means includes: an electrical igniter for igniting said fuel in said chamber. electrical means for effecting flow of combustion air to said chamber, and switching means operable to energize said igniter and electrical means independently of operation of the automobile engine whereby the heating system may be operated at normal output to heat the passenger compartment while the automobile engine is not running.

7. In a heater, a wick, means wetting a first end of the wick with fuel, an igniter adjacent the second end of said wick, a blower for passing combustion air past said second end, and means controlling said blower to delay starting thereof until the wick is ignited and to start the blower after the wick is ignited.

8. In a heater, a wick, means for igniting the wick comprising a hot wire electrical igniter adjacent said wick, a blower for effecting passage of combustion air across said wick to raise the flame thereof from contact with the wick, and electrical means for first energizin the igniter and after the wick is ignited then starting the blower.

9. In an automobile heater adapted to be mounted in an automobile having a source of fuel and a fire wall separating the engine compartment and the passenger compartment, a combustion chamber, fuel means adapted to be mounted in the engine compartment of the automobile and cooperating with the fuel supply of the automobile to effect passage of fuel to said combustion chamber, said means including means to conduct such fuel to said combustion chamber, control means adapted to be mounted in the passenger compartment of said automobile for varying the quantity of fuel delivered to said combustion chamber by said first-named means, said control means having a plurality of different calibrations which permit the control means to be positioned in predetermined manners that respectively effect different predetermined fuel flow rates, a sealed radiator adapted to be mounted in said passenger compartment, said radiator having an intake connected to said combustion chamber to receive burnt gases therefrom, said radiator having an exhaust end thereof, an exhaust pump connected to said exhaust end, a circulating fan adjacent said radiator, an electric motor having a horizontal shaft perpendicular to the fire wall and extending from said motor in opposite directions therefrom and carrying said fan on the end nearest the rear end of the car, the other end of said shaft being connected to said exhaust pump for operating the latter, said exhaust pump including means for exerting sufficient suction on said radiator to operate the latter below atmospheric pressure, said combustion chamber having inlets for combustion air, said exhaust pump being sufliciently powerful to cause flow of such combustion air into said chamber, said fuel means including means for effecting fuel passage to said chamber irrespective of the operation of said exhaust pump whereby the capacity of the exhaust pump need only be large enough to effect circulation of burnt gases and flow of combustion air, a hot wire resistance igniter mounted associated with said combustion chamber to ignite fuel therein, a shield adjacent said igniter for protecting the same from the cooling effect of the flow of combustion air in said chamber, a thermal switch in series with said igniter responsive to combustion to deenergize the igniter, and means adapted to be attached to the fire wall of an automobile for supporting said thermal switch, motor, exhaust pump, circulating fan, radiator, combustion chamber, igniter and shield whereby they are carried by the fire wall.

10. In an automobile heater, means including a combustion chamber for burning fuel, said means defining air inlet holes for supplying combustion air, a radiator having an intake connected to said chamber, said radiator having an outlet, an exhaust pump connected to said outlet and including means for exerting sufiicient suction on the radiator to draw combustion air in said inlet holes, an electrical hot wire igniter cooperating with said combustion chamber to ignite fuel therein, protective means for reducing the cooling effect of said combustion air on said hot wire igniter, means additional to said exhaust pump connected to the fuel supply of the automobile for conveying fuel flow to said combustion chamber, a conduit for supplying fuel to the last-named means, a circulating fan for passing air across said radiator, a motor having a shaft directly connected to said exhaust pump and circulating fan, a thermal switch responsive to combustion to deenergize said igniter, and means for mounting said radiator and circulating fan in the passenger compartment of an automobile.

11. In an automobile heater, means for burning fuel including a combustion chamber having an outlet, said means defining air inlet holes for conducting air to said chamber, a sealed radiator having an inlet connected to the outlet of said chamber, said radiator having an outlet, an eX- haust blower connected to said outlet for reducing the pressure in said combustion chamber and radiator below atmospheric pressure thereby effecting flow of combustion air in said air inlet holes, a circulating fan for blowing air to be heated over said radiator, means whereby said radiator and fan may be mounted in the passenger compartment of an automobile, an electric motor having a shaft directly coupled to said blower and fan, means operable independently H of said blower adapted for connection to the fuel supply of the automobile forconveying flow of fuel to said combustion chamber, a hot Wire igniter in said chamber for igniting the fuel, and

switching means adapted to be connected to the automobile battery for starting energization of said igniter and motor, said switching means including manually operable means for controlling the same and adapted for mounting in the passenger compartment of the automobile, said air inlet holes being of such small size that if the exhaust blower should stop the flame will go out.

12. The device defined by claim 3, in which said heat generating means includes: an electrical REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 65,010 Reynolds May 21, 1867 218,316 Robertson Aug. 5, 1879 221,733 House et al Nov. 18, 1879 445,789 Whittingham Feb. 3, 1891 471,866 Jones Mar. 29, 1892 588,669 Van Hoevenbergh Aug. 24, 1897 797,979 Sayre Aug. 22, 1905 1,408,433 Barrows Mar. 7, 1922 1,544,026 Morse June 30, 1925 1,583,238 Scudder May 4, 1926 2,172,667 Nelson Sept. 12, 1939 2,175,812 Meyerhofer Oct. 10, 1939 2,192,389 Treca Mar. 5, 1940 2,207,776 Black July 16, 1940 2,243,609 Spackman May 27, 1941 2,286,855 Holthouse June 16, 1942 2,308,887 McCollum Jan. 19, 1943 2,308,888 McCollum Jan. 19, 1943 2,333,602 Van Almelo Nov. 2, 1943 2,349,694 Barr May 23, 1944 

